Rotor size question

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Robert Hanford" <pomnept-at-comcast-dot-net> 

I am wondering if my 1/20 hsp. cap-start motor will handle a 7" x 1/4" 
phenolic rotor or if I should use a smaller one- say 4 1/2" to 6". It is a 
synch hysteresis and I've noticed in searching the archives that some have 
had trouble when the rotor is proportionaly too large. Any help will be 
greatly appreciated- this thing needs to get built %^ )
Why is a bigger rotor better? My next coil will be powered by two 
<mailto:15000k-at-60ma>15000k-at-60ma NSTs.
Thanks,
Robert Hanford